Refactoring result codes (#731)

* refactoring result codes

- Add a main enum who can handle some orphalin result codes and the default `ResultCode.Success` one.
- Add sub-enum by services when it's needed.
- Remove some empty line.
- Recast all service calls to ResultCode.
- Remove some unneeded static declaration.
- Delete unused `NvHelper` class.

* NvResult is back

* Fix

Ryujinx.HLE/HOS/ResultCode.cs

@@ -0,0 +1,12 @@
+namespace Ryujinx.HLE.HOS
+{
+    public enum ResultCode
+    {
+        OsModuleId     = 3,
+        ErrorCodeShift = 9,
+
+        Success = 0,
+
+        NotAllocated = (1023 << ErrorCodeShift) | OsModuleId
+    }
+}